"Alt-right" is short for "alternative right," to distinguish the movement from mainstream conservatism. It's often associated with efforts on the far right to preserve "white identity," oppose multiculturalism and defend "Western values."

She also accused the Republican nominee of "pushing discredited conspiracy theories with racist undertones" including suggesting that GOP primary candidate Ted Cruz's father was involved in the Kennedy assassination.

"A man with a long history of racial discrimination who traffics in dark conspiracy theories should never run our government of command our military," she added.

Trump took to social media following Clinton's speech, saying she was "pandering" and called her "fear-mongering."

Hillary Clinton's short speech is pandering to the worst instincts in our society. She should be ashamed of herself!

The Republican nominee's campaign says it has never used the term "alt-right" and disavows "any groups or individuals associated with a message of hate." The campaign suggested her attack was meant to distract from questions swirling around donations to The Clinton Foundation and her use of her private email servers.

"It's the oldest play in the Democratic playbook: say 'You're racist, you're racist, you're racist.' It's a tired, disgusting argument. It's the last refuge of the discredited Democratic politician."

Trump's campaign also responded with a strongly worded statement from a prominent black supporter, Pastor Mark Burns, who says Clinton and her campaign "went to a disgusting new low" with the video tying the Trump Campaign to "horrific racial images."